Single-phase commutator-motor.



E. P. W. ALEXANDERSON. SINGLE PHASE GOMMUTATOR MOTOR.

APPLICATION FILED JAN/7, 1908.

Patented Mar. 8, 1910.

Inventor Ernst F.

Witnesss:

Wires S ms Parr Fi ERNST r. w. ALEXANDERSON, or sciinnacraniz, new Yon-K, assienoa, no

GENERAL ELECTRIC COMPANY, A COFJEKQEALMQN .QF :NEW YQEK.

sINGLE-PHASE oommnzmtrozesmomon.

9511,35? Specification of Letters Patent. .Pamenfiged Mam, a

To all whom it mag concern:

Be it known that '1, Elmer F, W. ALEX- ANDERSON, a citizen of the United States,

residing at Schenectady, county of Schenec tady, State of New York, have invented certain new and useful Improvements in Single-Phase Commutatonll/IotorS, of which the s following is a specification.

My invention relates to single-phase closed in a prior patent No. 923,754, issued to .me June 1, 1909,-are started with the armature short-circuited, and for high; speeds have a shunt voltage impressed on the. armature. The -purpose of impressing the voltage on the armature is toreducethe' strength of the inducing field, which atelow speeds assists commutation by producing in} the armature coils short circuited by the brushes an electromotive force opposing the electromotive torce induced in these armature code by the action of the exciting windiiig, but which at high' speeds has an excess we and in urious efiect on commutation,

unless it is weakened in the manner above mentioned.

In addition to the electromotive' forces in the armature coils sliortcirc1-iited by the brushes in commutation, due to cutting the inducing field and to the transforineraction of the exciting field, there is the electromo-' tive force of commutation reactance, which becomes most serious at high speeds. If, when the shunt voltage 13 impressed on the arn'iature, the exciting winding is in circuit with the inducing winding, the armature ampere turns are in excess of the ampere turns of the inducing winding, so that leakage fields are produced, and these leakage fields, when out by the short-circuited armature coils, induce in them an electromotive force which assists the electromotive force of commutation reactance and increases its injurious effect on commutation. If the excitingwinding-is connected in circuit Withthe armature, ilistead'of with the inducing winding, the leakage fields 1') roduced-are in'the proper direction for producing an 'electro motive force-opposing that of commutation reactanee, so that the commutation is improved, but the amount of these leakage fields produced by :theexciting winding in having a pitch' correspondin ture ampere turns are evenly distributed Application filed January'7, 1908. Serial No. 409,699.

the armature circuit is hot alwaysgreat enough wholly to neutralize the effect of commutation reactance.

ilnprior patents Nos. 923,75 and "923,311, issued. to me June 1, 1909, I have disclosed a .motor construction in whichflthegcoils of the exciting windings are is distributed over the pole-faces, and in which an armature winding iseinp'loyed to the circumferential width of the. po e-taces. iPhe til) laced between 4 I the stator poles, and the .in ucing winding inotors of the commutator type having inducing and exciting windings on the stator, and while not necessarily limited to, is particu larly applicable to, motors which, as disuse of this fractional pitch results in producing commutation of the armature coils while these coils are under the pole-tips'of the stator.

My present invention consists in a motor arranged as above specified having its armature winding connected in a 'local closed circuit and its inducing windings so arran ed. that it produces a relatively excessive The efiect of this arrangement is such that even though the total armature ampere turns may exceed thetotal ampere turns of the-inducing winding, nevertheless,.since the armawhile those of the inducing wvinding are somewhat concentrated near the pole-tips,

the inducing winding is stronger than the armature winding at the pole-tips where commutation occurs. By means of this arran ement perfect commutation -may be obgained, whether'tlie exciting winding is connected in circuit with the inducingwinding or with the armature winding.

My invention will best be understood by reference to the accompanying drawings, in whichv Figure 1 shows diagrammatically "amend elevation, with thewinding partly "in'crosssection, of the upper half of a i'notor arranged in accordance with -my" invention; Fig. 2 shows "a modification of tl'ie same; Fi 3 is an explanatory diagram of fluxdistri utioiis; Fig. 4 is a diagram of connections with the excitin'g windingin the armature circuit; 1 and Fig.1) is a similar diagram with the'exciting'windiiig in circuit with the inducing winding. v

In "Fig. 1, A represents "the stator, which is of the usual laminated construction, B

represents the coils of the exciting winding,

' which are placed in large slots between the circumferential voles of the slator and C represents the inl a duci-ng winding, which is distributed in smaller slots on the poiefsces.

The distribution of the. ampere turns of the inducing winding is uneven, the greater portion of the turns being placed near the polo-tips, by forming the coils nearer the pole-tips with a greater number oi turns, as is shown most clearly in. the cross-sectional view at the rightdia-nd side of the figure.

D represents the armature provided with the commutator and brushes F. The Winding of armature D is arranged with the fractional nit h app o: instely equal to the wid of the stator polei uces. As wili be seen from 'lhis'drawiug, the coils undergoing cominuialien have their sides lying; directly beneath the pole-tips of the stator.

Fig. 2 is similar to Fig. 1, except that in place of using coils having different numbersof turns, the coils of the inducing windingare crowded toward the pole-tips. Vl liile this arrangement a somewhat different distribution finagnetomotive force of the inducing wind from the arrangement of Fig. 1, both arrangements result in producinga. relatively excessive magnetomotive force at the pole-tips.

The magnetic eii'ect oi the arrangements of- Figs. 1 and dis shown diugremmatically in Fig. In tliis figure a represents the outline of a stator-pole. The dotted line brep resents the resultant of the ampere turns of the inducing end armature windings, when I the inducing winding is evenly distributed, and its ampere turns are somewhat in excess of those, ofthe armature, as is the case when the exciting winding is connected in circuit with the inducing winding. The curve crepresents the resultant ampere turns of inducing and. armature windings when the inducing winding is unevenly,- distributed, as shown in Figs. 1 or 2. The uneven distribution of the inducing winding causes the armature ampere turns to predominate near the centeror the pole-face, but increases the predomination of the inducing ampere turns at the pole-tips; under which commutation is taking place, as indicated by the coil (Z, which represents a coil undergoingcommutation. It will be seen from Fig. 3 that by the uneven distribution of the inducing winding, the field of the inducing winding at the pole-tips can be increased to any amount desired for commutation, or, if the total ampere turns of the inducing-windingare less than those oi the armature which,

with on even distribution ofthe inducing windin would reverse the slope of the dottedinc F), Reducing iields it the pole tips in the wrong direction, the field at the pole-tips canbe reversed a-nd brought into the proper direction for commutation.

Fig. i shows :1 diagram of motor conneclions, which would produce distributions ol inagnetou'iotive force like those shown in Fig. 3. in this figure, the exciting winding 13 is included in the armature circuit, so that the total inducing ampere turns are in. cess of the armature ampere turns; and if the inducing winding were evenly distributed, the resultant ampere turns across the pole-faces would be as indicated by the dotted line 3) oil? Fig. 3, while, if the unevcu distribution oi? the inducing winding is adopted, the resultant ampere turns are as indicated by the curve (1.

It is not always desirable to connect the exciting winding in circuit with the armature winding, in which case the connectigms 01 Fig. 5 might be employed. in this cusc the exciting-winding B is in circuit with the inducing winding 0, end the total armature ampere turns are then in excess of the total ampere turns of the inducing winding. Consequently, the slope of the dotted line Z) in Fig. 3'would be reversed if the inducing winding were evenly distr'buted, and the re sulting field (it the pole-tips would be in the wrong direction for commutation; but, by proper arrangement'of the inducing winding, the distribution of smpcre turns represcnted by the curve 0 will still be produced, giving fields at the pole-tips of the proper direction for commutation, although near 'the center of the pole-face the fields Willi e in the opposite direction.

While I have used the term .induciug winding to designate that winding which induces a magnetomotive force in line with that of the armature, which term is ordinarily employed to designate that winding in repulsion motors, I wish it understood that I do not by the use of that termiiniit my invention to repulsion motors, but that in its broader aspects my invention is equally applicable to compensated series motors in which the winding in question is more quently termed a compensating winding.

hat I claim as new, and desire to secure by Letters Patent of the United States, is,

1. An alternating current motor, (:OlliPllS ing a stator, an exciting winding thereon, an inducing windingdistributed in slots on the faces of the poles of the exciting winding producing a relatively excessive mugnetizing effect at the pole-tips, an armature having the coils of its winding of a pitch approximately equal to the circumferential width of the pole-faces of: the exciting winding, a commutator and brushes the armature, and connections for including the armature in a local closed circuit.

2. An alternating current motor, comprisi35 fit-ifli'fl'ilfil, an exciting winding thereon, cu nducing winding unevenly distributed in slots on the feces of the poles or the or:-

' citins windin the, eater )ert of its effect ive ampere turns beingnear the pole-tips, an armature having the coils of its winding of a pitch approximately equal to the circumferential Width of the pole-faces of the exciting winding, a commutator and brushes for the armature, and connections for including the armature in a local closed circuit.

3. An alternating current motor, comprising a stator, an exciting winding thereon, an inducing winding distributed in slots on the faces of the poles of the exciting winding producing a relatively excessive mag"- netizing effect at the pole-tips, armature having the coils of its winding of a pitch approximately equal to the circumferential width of the pole faces of the exciting winding, a commutator and brushes for the armature, connections for including the armature in a local closed circuit, and a source of shunt voltage included in said connections.

4-. An alternating current motor, comprising a stator, an exciting winding thereon, an inducing winding unevenly distributed in slots on the faces of the poles of the exciting winding, the greater partof its effective ampere turns being nearthe poletips, an armature having the coils of its' winding of a pitch approximately equal to the circuinferential width of the pole-faces of the exciting winding, a commutator and brushes for the armature, and connections for including the armature in a local closed circuit viih a source of shunt volt-age.

An alternating current motor, comprising a stator, an exciting winding thereon, an inducing winding carried in slots on the faces of the poles of the exciting winding producing a relatively excessive. magnetizing ell'ect at the poletips, an armature having the coils of its winding of a pitch approximately equ'al tov the circumferential width of the pole-faces of the exciting winding, a commutator and brushes for the armature, and connections for connecting the armature in series with the stator windings and including the armature in a local closed circuit with the source of shunt voltage.

(L An alternating current motor, comprising a stator, an exciting winding thereon,

an inducing winding unevenly distributed in slots on the faces of the poles of the exciting winding, the greater part of its effective ampere turns being near the pole tips, an armature having the coils of its winding of a pitch approximately equal to the circumferential width of the pole-faces of the exciting winding, a commutator and brushes for the armature, and connections for connecting the armature in series with the stator windings and including the armature in a local closed circuit with a source of shunt voltage. 7. An alternating current motor, comprising a stator, an exciting winding thereon, an inducing winding carried in slots on the faces of the poles of the exciting Winding producing a relatively excessivemagnetizing effect at the pole-tips, an armature having the coils of its winding of a pitch approximately equal to the circumferential width of the pole-faces of the exciting winding, a commutator and brushes for the armature, and connections for connecting the armature in series with the stator windings and including the armature in a local closed circuit with the exciting winding andsa source of shunt voltage. I

8. An alternating current motor, comprising a stator, an exciting winding thereon, an inducing Winding unevenly distributed in slots on the faces of the poles of the exciting winding,'the greater part of its effective amperev turns being near the. poletips, an armature having the coils of its winding of a pitch approximately equal to the circumferential width of the pole-faces I ERNST r. w. ALEXANDERSON.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

